1. Field of the Invention
The present invention relates to a ballpoint tip for a ballpoint liquid container, such as a ballpoint refill using a ball as a writing medium.
2. Description of the Related Art
Most factors that determine the performance of a ballpoint liquid container for a ballpoint pen or the like are dependent on the accuracy of a ballpoint tip. A 0.7 mm diameter ball needs to rotate 44.5 full turns for drawing a line of only 10 cm, and a 0.5 mm diameter ball needs to rotate as many as 63.7 full turns for the same purpose at a very high rotating speed. Therefore, it is a very important problem with the ballpoint tip of this kind to prevent the abrasion of the ball friction necessarily caused by the high-speed rotation of the ball and the corrosional deterioration of the ball caused by static electricity generated by the high-speed rotation of the ball that occur as a logical consequence of the high-speed rotation of the ball, and to maintain the ability of the ball. If the ballpoint tip has problems in construction and accuracy, there is the possibility that "seepage" or "blotting" of the ink occurs.
A liquid applying implement disclosed in Japanese Utility Model provisional Publication No. Hei 5-76568 is an example of a ballpoint tip for a liquid container, such as a ballpoint refill of this kind. Referring now to FIG. 1, the liquid applying implement has a highly flexible liquid tank 14, and a ballpoint tip 12 provided with a ball 11 and connected to the liquid tank 14 by a connecting member 13 and a press-fit cylindrical member 17. The tank 14 contains a film-forming liquid of a high viscosity. The ball 11 is held for rotation in a forward end part of a body member of the ballpoint tip 12 so as to be partly exposed. A movable pin 15 having a small mass is placed in the body member of the ballpoint tip 12, and a spring 16 is compressed in the body member so as to push the movable pin 15 forward to press the ball 11 against the inner surface of the forward end part of the body member.
These prior art techniques applied to control a liquid, such as a gel employed in a gel ballpoint pen or a covering liquid use a ball pressing means including the movable pin formed by molding a resin, and a coil spring. These parts are difficult to assemble, springs have tendency to become tangled with each other when the pitches of the coils is greater than twice the diameter of the spring wire, and hence an automatic assembling machine cannot be used for assembling those parts, and the gel ballpoint pens or the like cannot be mass-produced.